We report the design and synthesis of a specific mitochondrial fluorescent probe AIE-MitoGreen-1 with AIE characteristics to monitor the mitochondrial morphology changes and identify the differentiation process of living brown adipose cells. The probe AIE-MitoGreen-1 has significant advantages such as high cell-permeability, good mitochondrial retention, low background fluorescence, large Stokes shift, and low toxicity.